1. Field of the Invention
The present invention relates to a chip antenna and, more particularly, to a chip antenna for use in mobile communication equipment used for mobile communications and local area networks (LAN).
2. Description of the Related Art
A conventional circularly-polarized-wave antenna 50 formed on a printed circuit board is generally structured as shown in FIGS. 8A and 8B. More specifically, a radiation conductor 52 made of a square-shaped radiation conductor film, a 90.degree. hybrid coupler 53 and two strip lines 54 and 55 are coated onto a printed circuit board 51. A non-reflective terminator 56 is mounted to one of the terminals of the 90.degree. hybrid coupler 53, and a matching circuit 57 is inserted between the output side of the 90.degree. hybrid coupler 53 and the strip lines 54 and 55. Further, a grounding radiation conductor film 59 is coated on the rear surface of the printed circuit board 51.
In the circularly-polarized-wave antenna 50, when a signal is input from a power feeding terminal 58, two outputs which have an equal amplitude and which are 90.degree. out of phase are fed from the 90.degree. hybrid coupler 53 through the matching circuit 57 to the strip lines 54 and 55. Since each of the strip lines 54 and 55 is connected to the central portion of the adjacent sides of the radiation conductor 52, electric currents excited by the strip line 54 and the strip line 55 flow intersecting at right angles on the radiation conductor 52, causing a circularly-polarized wave to be excited on the radiation conductor 52.
However, in the above-described conventional circularly-polarized-wave antenna, because, in addition to radiation conductors and strip lines, a 90.degree. hybrid coupler, a non-reflective terminator, a matching circuit and the like are required, the area required by one antenna becomes large. For this reason, there arises the problem that the mobile communication equipment in which the antenna is mounted becomes large. There is also another problem in that because a grounding radiation conductor film is coated on the rear surface of a base formed of printed circuit boards, a non-directional characteristic cannot be obtained.